[ChuckMcM]

No bartering is not illegal. Neither is buying, selling, and trading collectible Barbies. What is considered to be illegal (and I'm not a lawyer so I can't say definitively if it is or isn't) is creating an instrument, which represents a value (possibly fixed), and engaging in commerce using the instruments in lieu of the actual thing.

So trading a Malibu Barbie for a Space Barbie, or perhaps a Barbie Dream Home would not be a 'currency' transaction, giving someone a Malibu Barbie to pay for a lunch that was nominally $25 and having the person who got that Barbie then take it and buy $25 worth of groceries, and having the grocer be able to deposit it in their bank account and get credited with $25. That would be treating it like a currency.

There is a wonderful discussion on currency and what it is in the course Economics [1] offered by "The Great Courses". There is a wonderful story about an island which trades ownership interest in large rocks on another island as their currency. If you commute to work I highly recommend these courses as a way to pass the time and learn something (or at least get something to think about) while doing it. Don't be afraid of the price they regularly put things on sale for lots off. And if you have a library nearby you can sometimes check them out.

[1] http://www.thegreatcourses.com/tgc/courses/course_detail.asp...

update: I remember that one of the key things about the test of whether something was a currency or not, is if it could be exchanged back into another currency. Its one of the things various "points", "miles", and other systems avoid is an explicit path to turn them back into cash. Sure you can buy a $50 VISA gift card and sell it to someone for $50 but its not like you can go to the bank and turn it back into $50.

[Splines]

Planet Money had a segment about the rocks-as-currency island:.

Segment: http://www.npr.org/blogs/money/2011/02/15/131934618/the-isla...

Entire podcast (also discusses the currency test, IIRC): http://www.npr.org/blogs/money/2011/02/15/131963928/the-frid...

Very interesting.

[colanderman]

The Barbie example doesn't really make much sense. I could just as easily say I'm trading Malibu Barbie which is nominally worth $25 for a Space Barbie which is nominally worth the same, and run afowl of currency laws. Or that I'm trading Space Barbie for lunch with no mention of nominal worth and call it barter.

The test you propose about conversion is at least logically consistent, but it's not what I see applied. For example, Berkshares (local currency in the Berkshires) can be traded for USD but they don't run afowl of currency laws.